[Standards-JIG] Trying to understand

Matthias Wimmer m at tthias.eu
Thu May 18 21:00:26 UTC 2006


Hi Dave!


Dave Cridland schrieb:
> <presence from='user at example.com' to='jabber.org/jep0033'><addresses 
> xmlns='http://jabber.org/protocol/address'><address type='to' 
> jid='stpeter at jabber.org'/><address type='to' 
> jid='jer at jabber.org'/><address type='to' 
> jid='temas at jabber.org'/></addresses><show>xa</show><status>out for a 
> while</status><priority>0</priority></presence>
>>
>> Whouldn't that be okay for all of us? I think at least we should all 
>> be able to accept this protocol.
>>
>>
> Sorry, but no, I can't.
>
> Using your example:
>
> 1) Pre compression:
>
> JEP0033: 333 octets:
>
> "<presence from='user at example.com' to='jabber.org/jep0033'><addresses 
> xmlns='http://jabber.org/protocol/address'><address type='to' 
> jid='stpeter at jabber.org'/><address type='to' 
> jid='jer at jabber.org'/><address type='to' 
> jid='temas at jabber.org'/></addresses><show>xa</show><status>out for a 
> while</status><priority>0</priority></presence>"
>
> Normal: 408 octets:
>
> "<presence from='user at example.com' 
> to='stpeter at jabber.org'><show>xa</show><status>out for a 
> while</status><priority>0</priority></presence><presence 
> from='user at example.com' to='jer at jabber.org'><show>xa</show><status>out 
> for a while</status><priority>0</priority></presence><presence 
> from='user at example.com' 
> to='temas at jabber.org'><show>xa</show><status>out for a 
> while</status><priority>0</priority></presence>"
>
> This is not a massive saving.

My point was not this representation, I just used it as an example. My 
point was: Couldn't we agree on only sending out one stanza, but let the 
source server include the addresses to which they should be sent.
Sure JEP-0033 is a very verbouse way to express this, but shorter 
representations can be found for the same thing. E.g. the following 
could be used:

<presence from='user at example.com' to='stpeter at jabber.org jer at jabber.org 
temas at jabber.org'><show>xa</show><status>out for a 
while</status><priority>0</priority></presence>

(But this would require us to to escape existing spaces in the resource 
of a user - and it's also not a very beautiful way to extend XMPP. - But 
still it's just an example to show, that it can be expressed shorter.)
>
> 2) Post compression (using RFC1952):
>
> JEP0033 (as above): 175 octets.
> Normal (as above): 127 octets.
>
> Of course, this is skewed in favour of the existing method, because 
> it's compressed in isolation, but still, this is not a good result. 
> Worth exploring, but I don't think this works out, sorry. (Strangely, 
> I could tell the figures would work out like this just by looking at 
> the data. I must be working with compression *way* too much.)

If we would care about each bit on the wire, we would not use XML but a 
binary protocol, and we would have to use shorter tags. But that's not 
the philosophy of XML.


Tot kijk
     Matthias

-- 
Matthias Wimmer      Fon +49-700 77 00 77 70
Züricher Str. 243    Fax +49-89 95 89 91 56
81476 München        http://matthias.wimmer.name/




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